Follow-up: #41301
This commit is a rework and cleanup of the tools handling in Zephyr
CMake build system.
Instead of directly loading code a CMake modules for tool lookup, the
host tools now follows the CMake `find_package()` pattern for finding
programs / tools in module mode.
This makes it more clear which modules are responsible for finding tools
and which modules provides build integration / features.
The following tools can now be found using `find_package()`:
- Zephyr-sdk : find_package(Zephyr-sdk <version>)
- Generic host tools: find_package(HostTools)
This further allows us to decouple the `verify-toolchain` CMake script
part required by `twister` into a tool lookup module and a dedicated
CMake script which utilizes the lookup module.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>